Field of the Invention
The present invention relates to a method for manufacturing liquid ejection heads.
Description of the Related Art
Japanese Patent No. 4850637 discloses a method for manufacturing a liquid ejection head in which ejection port members are formed with silicon. This method allows ejection port members to be formed with silicon using the etching selection ratio of porous silicon to monocrystalline silicon by forming a porous silicon area, bonding a substrate thereto, and thereafter processing it from the back of the substrate.
The inventors examined a method disclosed in Japanese Patent No. 4850637 and found that the method has a problem in that forming ejection port members with a material different from that of its substrate causes stress due to a difference in the coefficient of thermal expansion, thus causing defects, such as a crack, in the substrate.